Travis CI update

Author: smarek

.travis.yml

@@ -1,17 +1,13 @@
 language: android
 sudo: false
-jdk: openjdk7
+jdk: openjdk8
 android:
   components:
-    - build-tools-23.0.1
+    - build-tools-28.0.3
     - extra-android-support
     - extra-android-m2repository
-    - android-23
+    - android-28
   licenses:
     - '.+'
 script:
-  # Sonatype bypass
-  - echo "nexusUsername=dummy" >> library/gradle.properties
-  - echo "nexusPassword=dummy" >> library/gradle.properties
   - ./gradlew clean assemble check
-  - ./gradlew :library:androidJavadocs